dzhokhar tsarnaev could face the death penalty. he was injured during arrest and is unable to speak. officers are asking him to respond to questions in writing. his 26 year old brother, tamerlan tsarnaev died in a standoff with officers. the brothers are ethnic chechens. they are trying to find out if they were planning further attacks or if they had accomplices. three people were killed and more than 170 were wounded in the marathon bombings. boston residents came together at the site of the bombings exactly one week later. more than 1,000 people gathered near the marathon finish line to mourn the dead. ♪ and the home of the brave >> people sang the national anthem, and they observed a moment of silence. >> i would like to understand what would drive a person to that kind of hatred so that perhaps we can prevent that kind of hatred in the future. >> mourners stopped to leave flowers. some were runners. some were friends or family of the dead or wounded. people across the country stopped at the same time to remember the victims.